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Huon Pine Collecting with the Tasmanian Seed Conservation Centre

Tasmania is home to ten conifer species, seven of which are endemic. Of these endemics, most reside in Tasmania’s highland and have been collected by the Tasmanian seedbank program. However one endemic from Tasmania’s lowland had not previously been collected. The Huon Pine (Lagarostrobos franklinii) is a temperate rainforest species of Tasmania’s wetter west and south, and an extremely slow growing and long-lived conifer with some individuals estimated to be over 2,000 years old. From the 1800’s timber was voraciously harvested for shipbuilding, as its timber is highly resistant to fungal and insect attacks. Today harvesting of living trees is illegal, but timber is still being extracted from trees that have been buried or drowned, in some cases for 100’s of years.

As part of the Millennium Seed Bank Partnership's Global Trees Project the Tasmanian Seed Conservation Centre based at the Royal Tasmanian Botanical Gardens decided to target this iconic species. Due to the historic logging and slow growth rates finding easily accessible, mature, healthy populations was presumed to be the biggest hurdle to successfully collecting this target. A second potential problem was that this species was reputed to be a “masting” species, i.e. a plant that produces seed sporadically every several years. As luck would have it however in the process of trying to identify suitable populations for three other Global Trees Project targets we found a potentially suitable population growing along the banks of the Pieman River on Tasmania’s west coast.

Stopping at Corinna, an old miners town that is now an eco-resort, a walk along the river bank revealed that there might be enough mature plants fruiting to make collecting possible. The following day we took a river cruise to get a better idea of what was going on. The boat staff were happy to help and we inspected a number of plants along the river to assess what was going on. Lagarostrobos is a single sexed plant, so not every plant you drive up to will be bearing seed. The coxswain was confident that they could tell male and female trees just from their habit (it is generally believed that female trees are more pendulous). This survey revealed that this was not the case and sex determination could only be made by a closer inspection of the trees, as male strobili and female cones are very similar in size and density. However, surveying with the Sweetwater boat revealed it to be a great means to collect seed. The boat proved to be stable and very capable of getting in close to the river bank and to the trees thus allowing us to collect. Time was going to be an issue as we had to inspect each tree to determine sex and that obviously reduces our effective collecting time with the few hours we could have on the boat. Fortunately, single sexed plants are obligate outbreeders (for obvious reasons) and this changes the requirement for collecting. In obligate outbreeding plants sampling from 30 individuals, rather than our typical target of 50, should be sufficient to adequately capture the genetic diversity of a population.

When we returned to Corinna in January a quick inspection of the Lagarostrobos growing in the resort revealed that it was ready to collect. We quickly had a chat with the resort staff and booked a trip on the Sweetwater boat the next afternoon to collect the seed from trees growing along the river. In the two and half hour boat trip, we collected over 92,000 viable seeds from 32 trees of Lagarostrobos. This is a fantastic result for such an important, iconic and restricted tree.